Filled methacrylate systems already are known to the prior art. The use of mixtures based on monomeric esters of methacrylic acid and fillers as casting compositions for the preparation of optionally glass fiber reinforced molded bodies and profiles is known from Published German Patent Application DE-OS-20 28 890. The mixture according to DE-OS-20 28 890 comprises essentially a) approx. 5 to approx. 50% by wt. of monomeric esters of methacrylic acid with mono- and/or polyhydric alcohols, although optionally up to approx. 20% by wt. of the methacrylic acid esters may be replaced by other, polymerizable vinyl or allyl compounds, and b) approx. 95 to approx. 50% by wt. of one or more inorganic or organic solids which are insoluble in the monomer or in the monomer mixture. The mixture may, in addition, contain minor quantities of dyes or pigments and, if necessary, polymerization accelerators. The mixture is cured, preferably with the action of known polymerization catalysts. DE-OS 20 28 890 proposes metal powder, inter alia, as a filler. For example, the use of finely divided iron powder or aluminum powder is described.
The well known casting compound is not very suitable as a floor coating because of the low proportion of monomer and the high filler content.
U.S. Pat. No. 3,907,727 discloses the use of carbon black for blacking molded bodies made from cast acrylate polymer. According to this patent, a dispersion of furnace black, acrylate polymer, methyl methacrylate monomer and a small proportion of nitrocellulose is prepared. Then, a catalyst is added to the dispersion. The dispersion is then poured into the mold and heated to at least 50.degree. C.
In view of the addition of nitrocellulose and the relatively high temperature required for polymerization, this system is also unsuitable as a floor coating.
Filled polymer materials, e.g. mixtures of polybutyl methacrylate and CP-butyl acrylate-isobutylene which are filled with Ni powder, Al powder or graphite, are known from DKI, report no. 93040679707, 1993-04779. The Russian publication on which said abstract is based is concerned with the analysis of the elongation diagram of filled polymer materials. There is no references to floor coatings in the DKI abstract.
Published German Patent Application DE-OS 23 09 149 is concerned with polymer compositions in which the surface of a granular, inorganic substance is coated almost completely with a polymer material. Inorganic substances mentioned are, inter alia, iron sesquioxide or carbon, while monomers listed are methyl methacrylate or acrylic acid methyl ester. In an example, however, only iron sesquioxide particles are coated with pollvinyl chloride, which is polymerized at a temperature of 65.degree. C. According to DE-OS 23 09 149, a heat-setting methacrylate system is used, while the inorganic particles mentioned are provided with a polymer coating in order to produce a better strength during pressing than, for example, dry mixtures of inorganic substances and synthetic resin would achieve.
Finally, a process for the polymerization of methyl methacrylate in the presence of graphite is known from Angewandte Chemie 53 (1976), pages 65-72. Polymerization is carried out in SO.sub.2 -containing water, a reaction between ash contained in graphite and HSO.sub.3.sup.- being assumed as an initiating reaction. The aqueous redox system used in this publication does not seem to be suitable for the preparation of conductive floor coatings.
For some decades, electrically conductive floor coatings have been prepared from of epoxides, polyurethanes or polyesters. In order to achieve conductivity, conductive fillers such as carbon black, graphite or surface-treated metal powders are added to the coatings. On the other hand, when attempts have been made to base such coatings on (meth)acrylates, such additions lead to disturbances in the curing process, with the result that corresponding conductive floor coatings based on (meth)acrylate could not be produced.
The preparation of conductive, acrylic (meth)acrylate coatings was, therefore, very expensive. U.S. Pat. No. 4,714,569 describes a coating process in which graphite and carbon black are pre-polymerized in a particular ratio with (meth)acrylic acid and functionalized (meth)acrylates, the mixture is further polymerized with an azo compound at elevated temperature, and the product obtained is cured with a cross-linking agent. This process is unsuitable for coating large areas, particularly floors, because a temperature of between 80.degree. and 90.degree. C. over several hours was required. It is impractical to achieve such temperatures over large areas.